Accepted Manuscript
External Validation of the European Hernia Society Classification for PostoperativeComplications after Incisional Hernia Repair: A Cohort Study of 2,191 Patients
Leonard F. Kroese, MD, Gert-Jan Kleinrensink, PhD, Johan F. Lange, MD, PhD,Jean-Francois Gillion, MD
PII: S1072-7515(17)32119-1
DOI: 10.1016/j.jamcollsurg.2017.11.018
Reference: ACS 8948
To appear in: Journal of the American College of Surgeons
Received Date: 24 August 2017
Revised Date: 13 November 2017
Accepted Date: 20 November 2017
Please cite this article as: Kroese LF, Kleinrensink G-J, Lange JF, Gillion J-F, and the Hernia-Club,External Validation of the European Hernia Society Classification for Postoperative Complications afterIncisional Hernia Repair: A Cohort Study of 2,191 Patients, Journal of the American College of Surgeons(2018), doi: 10.1016/j.jamcollsurg.2017.11.018.
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External Validation of the European Hernia Society Classification for Postoperative Complications after Incisional Hernia Repair: A Cohort Study of 2,191 Patients Leonard F Kroese, MD1, Gert-Jan Kleinrensink, PhD2, Johan F Lange, MD, PhD1, Jean-Francois Gillion, MD3, and the Hernia-Club 1Department of Surgery, Erasmus University Medical Center Rotterdam, the Netherlands 2Department of Neuroscience, Erasmus University Medical Center Rotterdam, the Netherlands 3Unité de Chirurgie Viscérale et Digestive, Hôpital Privé d’Antony, Antony, France Members of The Hernia-Club are listed in the Appendix Disclosure Information: Nothing to disclose. Corresponding author and reprint requests: Leonard Kroese, MD Erasmus University Medical Center, Rotterdam Department of Surgery Room Ee-173 PO BOX 2040, 3000 CA Rotterdam, the Netherlands Telephone number: +31 10 7043683 E-mail address: [email protected] Brief title: Validity of European Hernia Society Classification
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Abstract
Background: Incisional hernia is a frequent complication after midline laparotomy. Surgical
hernia repair is associated with complications, but no clear predictive risk factors are
identified. The European Hernia Society (EHS) classification offers a structured framework
to describe hernias and to analyze postoperative complications. Because of its structured
nature, it might prove to be useful for preoperative patient or treatment classification. The
objective of this study was to investigate the EHS classification as a predictor for
postoperative complications after incisional hernia surgery.
Study design: An analysis was performed using a registry-based, large-scale, prospective
cohort study, including all patients undergoing incisional hernia surgery between September
1st 2011 and February 29th 2016. Univariate analyses and multivariable logistic regression
analysis were performed to identify risk factors for postoperative complications.
Results: A total of 2,191 patients were included, of whom 323 (15%) patients had one or
more complications. Factors associated with complications in univariate analyses (p<0.20)
and clinically relevant factors were included into the multivariable analysis. In the
multivariable analysis, EHS width class, incarceration, open surgery, duration of surgery,
Altemeier wound class, and therapeutic antibiotic treatment were independent risk factors for
postoperative complications. Third recurrence and emergency surgery were associated with
fewer complications.
Conclusion: Incisional hernia repair is associated with 15% complications. The EHS width
classification is associated with postoperative complications. To identify patients at risk for
complications, the EHS classification is useful.
Keywords: incisional hernia, hernia repair, complications, risk factors
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Introduction
Incisional hernia remains a frequent complication after abdominal surgery with
incidence rates of 10-30% after midline laparotomies, depending on risk factors.(1-6) This
incidence leads to a high number of hernia repair operations. In the USA alone, over 300,000
repairs are performed annually. The associated costs of these hernia repairs are estimated to
be US$3.2 billion a year.(7) Incisional hernias can be surgically repaired for many reasons;
patients can have cosmetic complaints, pain, bowel obstruction, mechanical complaints or
incarceration.
There is a great variety of incisional hernias with different locations, width, and
length. To categorize these hernias, the European Hernia Society (EHS) developed and
published the ‘Classification of primary and incisional abdominal wall hernias’ in 2009.(8)
One of the aims of this classification was to use a uniform method of describing hernias in
both scientific and clinical communication. It combines the location and size of the hernia.
For location, differentiation between midline, lateral, or combined is made. For the size, the
width of the hernia is used. This is divided into three subgroups: W1 (<4cm), W2 (4-10cm),
and W3 (>10cm). The classification is partly based on the estimated risk of complications
and recurrences. Although published several years ago, the EHS classification has not been
externally validated thoroughly.
Several studies have addressed the issue of postoperative complications after
incisional hernia repair,(9-11) but these studies did not correct for any risk factors or did not
use any size classification such as the EHS classification.
The objective of this study was to evaluate the EHS classification amongst other
factors, as a potential predictive tool for postoperative complications after incisional hernia
surgery, by using a large-scale database. It was hypothesized that a higher hernia width class
would lead to more postoperative complications.
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Methods
Study design
A retrospective analysis of a registry-based, large-scale, prospective cohort was
performed. Using the French Hernia-Club registry, all adult patients undergoing incisional
hernia surgery between September 1, 2011, and February 29, 2016, were included. The
Hernia-Club registry is approved by the French ‘Commission Nationale de l’Informatique et
des Libertés’ (CNIL; registration number 1993959v0). Because the study is a registry-based
study, and patient data is anonymized, additional participant consent and institutional review
board approval were not required in accordance to the French and Dutch national ethical
standards.
STROBE (Strengthening the Reporting of Observational studies in Epidemiology)
recommendations for the reporting of observational studies as well as the European Registry
of Abdominal Wall Hernias (EuraHS) recommendations were used for this study.(12, 13)
Hernia-Club registry
The Hernia-Club registry is a collaborative, prospective, anonymized online database
of all abdominal wall hernia surgery procedures performed by 42 French surgeons with a
specific interest in abdominal wall surgery. Each participating surgeon must accept and sign
the Charter of Quality, which states that: ‘‘all input must be registered in a consecutive,
unselected, and exhaustive manner and in real time’’. Participants consent to random peer
review of original medical charts. A total of 164 parameters are collected prospectively from
screening, pre-, peri- and postoperative periods. Parameters are directly collected online by
the operating surgeon in real time. Postoperative outcomes are collected by the surgeon and
are further checked by an independent clinical research associate (CRA) during the 2-year
follow-up. The CRA is blinded for operative techniques used. In case of discrepancies, the
medical record is checked.
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All parameters collected in this database are fully compatible with the European
Hernia Society (EHS) classification of primary and incisional abdominal wall hernias(8) and
the European Registry of Abdominal Wall Hernias (EuraHS) international online
platform.(14)
Data collection
Data extracted from the registry included patient age, sex and other patient
characteristics (body mass index (BMI), smoking habits, diabetes mellitus (DM),
corticosteroid use, preoperative radio- or chemotherapy, history of aneurysm of the
abdominal aorta (AAA), connective tissue disorders, anticoagulants use or coagulopathies,
previous other abdominal wall hernias, American Society of Anesthesiologists score (ASA));
hernia characteristics (location, width, length, EHS width class, primary or recurrent hernia),
and surgical characteristics (open or laparoscopic, emergency surgery, mesh use and
technique of mesh placement, duration of surgery, and Altemeier wound classification(15)
(clean/clean contaminated/contaminated/dirty)).
Outcome
The primary outcome measure was the number of patients with postoperative
complications within 30 days after surgery. Postoperative complications were graded using
the Clavien-Dindo grading system.(16)
Statistics
SPSS 21.0 (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, version
21.0. IBM Corp, Armonk, NY, USA) was used for all statistical analyses. Normal
distribution of continuous variables was assessed and Levene’s test for equality of variances
was used. Continuous variables are presented as means with standard deviations (SDs) or
median with interquartile range (IQR). Categorical variables are presented as numbers with
percentages. Mann-Whitney U (continuous data) and chi-squared tests (categorical data) were
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used to analyze risk factors for complications after incisional hernia surgery. In case of small
groups (n<5), Fisher’s exact test was used. Potential risk factors that were related to
postoperative complications in the univariate analysis (p<0.20) and clinically relevant factors
often described in hernia publications were included in the multivariable logistic regression
analysis. To prevent bias and to increase statistical power, multiple imputations were
performed to compensate for missing data. In the multivariable analysis, p-values <0.05 were
considered as statistically significant.
Results
A total of 2,191 patients with an incisional hernia were included in this study.
Baseline patient characteristics are presented in Table 1. Most notable, age, BMI, smoking,
diabetes mellitus, and ASA class were not statistically significantly different between patients
with or without complications. Patients with a postoperative complication had statistically
significantly fewer primary ventral hernias in their medical history (12% versus 17%,
p=0.021). Other factors were not statistically significantly different.
Postoperative complications
Of the 2,191 patients, 323 patients (15%) developed one or more postoperative
complications. Of these 323 patients, most patients had a wound complication (166 patients,
51% of all complications), followed by medical complications (137 patients, 42% of all
complications) and surgical complications (93 patients, 29% of all complications). All 30-day
postoperative outcomes are presented in Table 2.
Hernia characteristics
Hernia characteristics are presented in Table 3. There were significant differences in
EHS width classification between patients with or without postoperative complications
(p<0.001) with more W1 class hernias (<4 cm) in the group without complications and more
W3 class hernias (>10 cm) in the group with complications. Most hernias were located in the
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midline. The location of hernias, the recurrences, and previous mesh placement were not
significantly different between patients with or without postoperative complications.
Surgical characteristics
Surgical characteristics are presented in Table 4. Patients with complications had
more incarcerated hernias (7.7% versus 3.0%, p<0.001), fewer laparoscopic procedures (12%
versus 29%, p<0.001), and different mesh locations (p<0.001). Operating time was longer in
the complication group (80 minutes (IQR 45-120) versus 45 minutes (IQR 24-75), p<0.001).
Additionally, Altemeier wound class(15) and antibiotic treatment were also significantly
different (both p<0.001). Emergency surgery rates and primary suture rates were not
significantly different.
Multivariable analysis
After univariate analysis, ten imputations were performed to reduce bias, caused by
missing data and to increase statistical power. The imputed data was then used for logistic
regression analysis. All factors with a p-value <0.20 and all clinically relevant factors were
used for the multivariable analysis, identifying factors significantly associated with
complications. The result of the multivariable analysis is shown in Table 5.
After correcting for possible confounding variables in the multivariable logistic
regression analysis, the following factors remained statistically significant: EHS width class
(W2: odds ratio (OR) 1.448 (95% confidence interval (CI) 1.064-1.971), p=0.019; W3: OR
2.090 (95% CI 1.375-3.179), p=0.001), third recurrence (OR 0.369 (95% CI 0.144-0.941),
p=0.037), emergency surgery (OR 0.207 (95% CI 0.068-0.631), p=0.006), incarceration (OR
3.187 (95% CI 1.199-8.467), p=0.020), open surgery (OR 2.060 (95% CI 1.408-3.015),
p<0.001), duration of surgery (OR 1.006 (95% CI 1.004-1.009), p<0.001), Altemeier wound
class (clean contaminated: OR 2.179 (95% CI 1.225-3.877, p=0.008; contaminated: OR 2.855
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(95% CI 1.074-7.585, p=0.035; dirty: OR 6.346 (95% CI 1.442-27.938), p=0.015), and
therapeutic antibiotic treatment (OR 2.391 (95% CI 1.289-4.438), p=0.006).
Discussion
In this analysis of a large-scale prospective French database of 2,191 patients
undergoing incisional hernia surgery, EHS width class, incarceration, open surgery, duration
of surgery, Altemeier wound class, and therapeutic antibiotic treatment were independent risk
factors for postoperative complications. Emergency surgery and the presence of a third
recurrence were found to be factors leading to a lower risk of postoperative complications.
The complication rate of 15% found in this study was comparable to the 2009 study by
Bisgaard et al. reporting complication rates of 10.7%.(11)
Hernia size has been identified as a risk factor for postoperative complications
before.(10) Larger hernias mean more extensive dissection, larger meshes, and increased
operating time. For ease of use, the EHS classification contains only three classes instead of
the absolute size.
The EHS classification has previously been studied as a predictor for wound
complications.(17) In this 2015 study by Baucom et al., 538 patients were analyzed and
compared, based on EHS location (midline or lateral). They found that postoperative
complications were more likely to occur in midline hernias than in lateral hernias. However,
the EHS classification was not used in more detail. Our study uses both the location of the
hernia as well as the size class. After multivariable analysis, the hernia location was no
statistically significant risk factor for postoperative complications. This different finding
might be explained by the fact that Baucom et al. only performed univariate analyses and no
multivariable analysis.
The other statistically significant findings; incarceration, open surgery, duration of
surgery, Altemeier wound class, and therapeutic antibiotic treatment all reflect the situation
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of more complicated surgery. Especially wound contamination is more likely to lead to
surgical site infections in these cases. In 2016, Petro et al.(18) suggested to include
contamination in a hernia risk model. This is in line with the findings of this study.
Duration of surgery was associated with a higher risk of complications. It could be argued
that duration of surgery could also be considered as a kind of an outcome measure.
Emergency surgery was associated with fewer complications in the multivariable analysis.
However, this is possibly due to adjusting for confounders related to emergency surgery
(incarceration, open surgery, Altemeier wound classification, and antibiotic treatment).
In general, there was a non-significant trend of fewer complications after more recurrent
hernias. The only statistically significant difference in the third recurrence is probably
associated with the relatively small group size (n=5 with third recurrences in the
complications group) and does not reflect a clinically relevant finding.
This study demonstrates that there is a great variance within all patients with an
incisional hernia. Although this might not sound surprising, it is of paramount importance to
stress that hernia research should not investigate all patients with an incisional hernia as a
homogeneous group. Given the great differences in outcomes, studies should divide their
patients into subgroups, based on the EHS classification, or the EHS classification should be
considered when determining inclusion or exclusion criteria for new studies. Using the EHS
classification in research might reduce heterogeneity in results of studies on incisional hernia.
It might also allow readers to appreciate results better by comparing different study
populations based on the EHS classification. Although not evaluated in this study, the EHS
classification might be a framework to use for tailored hernia care. An important step in this
direction has recently been taken by Dietz et al.(19) by adjusting treatment based on a
preoperative risk assessment. In this article, risk-adjusted procedure tailoring ensured that
high-risk patients did not have a higher rate of postoperative complications. This research
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direction is an important one to investigate. Hernia surgery, especially when conducted
electively, is considered to be relatively low-risk surgery. Fortunately, this is the case for
most patients, but the results found in this study show that specific subgroups can have worse
outcomes.
Limitations
There are several limitations to this study. First, the results of this study are not based
on randomized data. This gives a potential risk of selection. However, the benefit of this kind
of registry study is the translation to the real clinical situation: no artificial selection has been
made in patient inclusion. Second, this study focuses on postoperative complications.
However, this only covers part of the outcomes of hernia repair. A second, long-term analysis
should study whether the EHS classification could be used to predict recurrences or
reoperations as well. Such a study might require combining different large-scale cohort
studies to achieve the statistical power needed.
Conclusion
The width classification of the EHS classification of incisional hernias is an
independent risk factor for complications after incisional hernia repair. Therefore, the EHS
classification should be used in studies reporting on incisional hernia repair. Surgeons should
also use the classification for preoperative risk assessment. To achieve this, emphasis should
be put on the simplicity of the classification. A next step will be to analyze different
treatment strategies for patients from different EHS classes in an attempt to lower the overall
postoperative complication rate effectively.
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Appendix:
Members of The Hernia-Club: Ain J-F, Polyclinique Val de Saone, Macon, France; Beck M,
Clinique Ambroise Paré, Thionville, France; Barrat C, Hôpital Universitaire Jean Verdier,
Bondy, France; Berney C, Bankstown-Lidcombe Hospital, Sydney, Australia; Berrod J-L,
Groupe Hospitalier Paris St Joseph, Paris, France; Binot D, MCO Côte d’Opale, Boulogne
sur Mer, France; Boudet M-J, Clinique Alleray-Labrouste, Paris, France; Bousquet J, Hôpital
Privé de la Chataigneraie, Montpellier, France; Blazquez D, Clinique Jeanne d’Arc, Paris,
France; Bonan A, Hôpital Privé d’Antony, Antony, France; Cas O, Centre Médico
Chirurgical –Fondation WALLERSTEIN, Arès, France; Champault-Fezais A, Groupe
Hospitalier Paris St Joseph, Paris, France; Chastan P, Bordeaux, France; Cardin J-L,
Polyclinique du Maine, Laval, France; Chollet J-M, Hôpital Privé d’Antony, Antony, France;
Cossa J-P, CMC Bizet, Paris, France; Dabrowski A, Clinique de Saint Omer, Saint Omer,
France; Démaret S, Clinique Saint Vincent, Besançon, France; Drissi F, CHU Nantes,
Nantes, France; Durou J, Clinique de Villeneuve d’Ascq, Villeneuve d’Ascq, France; Dugue
T, Clinique de Saint Omer, Saint Omer, France; Faure J-P, CHRU Poitiers, Poitiers, France;
Framery D, CMC de la Baie de Morlaix, Morlaix, France; Fromont G, Clinique de Bois
Bernard, Bois Bernard, France; Gainant A, CHRU Limoges, Limoges, France; Gauduchon L,
CHRU Amiens, France; Genser L, CHU Pitié-Sampétrière, Paris, France; Gillion J-F, Hôpital
Privé d'Antony, Antony, France; Guillaud A, Clinique du Renaison, Roanne, France; Jacquin
C, CH du Prado, Marseille, France; Jurczak F, Clinique Mutualiste, Saint Nazaire, France;
Khalil H, CHRU Rouen, Rouen, France; Lacroix A, CH de Auch, Auch, France; Ledaguenel
P, Clinique Tivoli, Bordeaux, France; Lepère M, Clinique Saint Charles, La Roche-sur-Yon,
France; Lépront D, Polyclinique de Navarre, Pau, France; Letoux N, Clinique Jeanne d’Arc,
Paris, France; Loriau J, Groupe Hospitalier Paris St Joseph, Paris; Magne E, Clinique Tivoli,
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Bordeaux, France; Ngo P, Hôpital Américain, Neuilly, France; Oberlin O, Croix St Simon
Diaconesses, Paris, France; Paterne D, Clinique Tivoli, Bordeaux, France; Pavis d’Escurac X,
Strasbourg, France; Potiron L, Clinique Jules Verne, Nantes, France; Renard Y, CHRU
Reims, Reims, France; Soler M, Polyclinique Saint Jean, Cagnes-sur-Mer, France; Rignier P,
Polyclinique des Bleuets. Reims; Roos S, Clinique Claude Bernard, Albi, France; Thillois J-
M, Hôpital Privé d’Antony, Antony, France; Tiry P, Clinique de Saint Omer, Saint Omer,
France; Verhaeghe R, MCO Côte d’Opale, Boulogne sur Mer, France; Vu P, Hôpital Privé
Marne-la-Vallée-Brie-sur-Marne, France; Zaranis C, Clinique de la Rochelle, La Rochelle,
France
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Table 1.Baseline Characteristics
Variable No complication
(n=1813)
Missing Any complication
(n=323)
Missing p Value
Age, y, mean (SD) 62.77 (14.01) 6 (0.3) 63.94 (14.09) 2 (0.6) 0.155 Male sex, n (%) 865 (48) 0 151 (47) 0 0.750 BMI, kg/m2, mean (SD) 29.03 (6.85) 0 29.94 (7.92) 0 0.069 Smoking, n (%) 315 (17) 98 (5.4) 63 (20) 20 (6.2) 0.319 Diabetes mellitus, n (%) 216 (12) 39 (2.2) 46 (14) 7 (2.2) 0.239 Corticosteroid use, n (%) 63 (3.5) 39 (2.2) 12 (3.7) 7 (2.2) 0.828 Radiotherapy, n (%) 33 (1.8) 39 (2.2) 5 (1.5) 7 (2.2) 0.733 Chemotherapy, n (%) 107 (5.9) 39 (2.2) 22 (6.8) 7 (2.2) 0.527 AAA, n (%) 12 (0.7) 15 (0.8) 5 (1.5) 2 (0.6) 0.100 Connective tissue disorder, n (%)
6 (0.3) 15 (0.8) 1 (0.3) 1 (0.3) 0.949
Anticoagulants use or coagulopathy, n (%)
289 (16) 39 (2.2) 65 (20) 7 (2.2) 0.062
Presence of ascites, n (%) 10 (0.6) 19 (1.0) 4 (1.2) 4 (1.2) 0.249 ASA Class, n (%) 0.096
I-II 1249 (69) 208 (64) III-IV 554 (31) 114 (35) Missing 10 (0.6) 1 (0.3)
Previous other abdominal wall hernia, n (%)
Inguinal hernia 196 (11) 28 (8.7) 0.242 Primary ventral hernia 299 (17) 37 (12) 0.021 Incisional hernia 313 (17) 68 (21) 0.105 Other abdominal wall hernia
46 (2.6) 8 (2.5) 0.945
Missing 15 (0.8) 2 (0.6) Hiatal hernia, n (%) 52 (2.9) 15 (0.8) 12 (3.7) 2 (0.6) 0.414 Family history of hernia, n (%) 15 (0.8) 15 (0.8) 2 (0.6) 2 (0.6) 0.696 AAA, aneurysm of the abdominal aorta; ASA, American Society of Anesthesiologists
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Table 2. Outcomes
Characteristic Frequency N missing
Admission duration, d, mean (SD)
4.3 (4.6) 0
Patients with ≥1 complication within 30 days, n (%)
323 (15) 2 (0.09)
Wound complications 166 (7.6) Surgical complications 93 (4.2) Medical complications 137 (6.3)
Clavien-Dindo grade (16), n (%) <III 176 (54) ≥III 51 (16) Unknown 96 (30)
30-day mortality, n (%) 2 (0.1) SD, standard deviation; ICU, intensive care unit
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Table 3. Hernia Characteristics
Characteristic No complication
(n=1813)
Missing Any complication
(n=323)
Missing p Value
Hernia location, n (%) 0.119 Midline 1037 (57) 209 (65) Lateral 194 (11) 27 (8.4) Combined 71 (3.9) 9 (2.8) Missing 511 (28) 78 (24)
EHS width classification(8), n (%)
<0.001
W1: <4 cm 899 (50) 94 (29) W2: 4-10 cm 700 (39) 146 (45) W3: >10 cm 168 (9.3) 70 (22) Missing 46 (2.5) 13 (4.0)
Recurrent hernia, n (%)
366 (20) 31 (1.7) 68 (21) 6 (1.9) 0.712
Number of recurrences, n (%)
0.051
First recurrence 268 (15) 52 (16) Second recurrence 63 (3.5) 7 (2.2) Third recurrence 31 (1.7) 5 (1.5) Fourth or more recurrence
4 (0.2) 4 (1.3)
Missing 35 (1.9) 10 (3.1) Previous mesh, n (%) 610 (34) 25 (1.4) 113 (36) 6 (1.9) 0.597 EHS, European Hernia Society
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Table 4. Surgical Characteristics
Characteristic No complication
(n=1813)
Missing Any complication
(n=323)
Missing p Value
Emergency procedure, n (%)
69 (3.8) 7 (0.4) 18 (5.6) 3 (0.9) 0.133
Incarceration, n (%) 53 (3.0) 57 (3.1) 24 (7.7) 1 (3.4) <0.001 Laparoscopic procedure, n (%)
519 (29) 26 (1.4) 37 (12) 6 (1.9) <0.001
Primary suture closure, n (%)
183 (10) 55 (3.0) 40 (13) 22 (6.8) 0.137
Mesh location, n (5) <0.001 Intraperitoneal 1084 (62) 136 (45) Sublay 447 (26) 101 (34) Onlay 37 (2.1) 20 (6.7) Component separation with mesh
4 (0.2) 3 (1.0)
Missing 55 (3.0) 22 (6.8) Duration of surgery, min, median (IQR)
45 (25-75) 23 (1.3) 80 (45-120) 7 (2.2) <0.001
Altemeier wound classification(15), n (%)
<0.001
Clean 1735 (96) 277 (86) Clean contaminated 57 (3.1) 28 (8.7) Contaminated 12 (0.7) 11 (3.4) Dirty 4 (0.2) 7 (2.2) Missing 5 (0.3) 0
Antibiotic treatment, n (%)
<0.001
None 383 (21) 43 (13) Prophylactic 1355 (75) 240 (74) Therapeutic 66 (3.6) 37 (12) Missing 9 (0.5) 3 (0.9)
IQR, interquartile range
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Table 5. Multivariable Analysis
Variable OR 95% CI p Value Age 1.007 0.996-1.017 0.223 Female sex 1.138 0.870-1.488 0.345 BMI 1.013 0.994-1.033 0.168 Smoking 1.334 0.952-1.870 0.094 Diabetes 0.914 0.618-1.351 0.650 AAA 2.192 0.671-7.165 0.194 Anticoagulants 1.237 0.867-1.763 0.240 ASA III&IV vs I&II 1.090 0.807-1.473 0.573 History of primary ventral hernia 0.763 0.509-1.143 0.190 History of incisional hernia 1.009 0.654-1.554 0.969 EHS location
Midline 1.000 Lateral 0.718 0.440-1.170 0.180 Combined 0.514 0.252-1.045 0.066
EHS width class W1: <4cm 1.000 W2: ≥4-10cm 1.448 1.064-1.971 0.019 W3: >10cm 2.090 1.375-3.179 0.001
Number of recurrences First recurrence 1.000 Second recurrence 0.831 0.530-1.303 0.420 Third recurrence 0.369 0.144-0.941 0.037 Fourth or more recurrence 0.455 0.157-1.318 0.146
Emergency procedure 0.207 0.068-0.631 0.006 Incarceration 3.187 1.199-8.467 0.020 Open vs laparoscopic procedure 2.060 1.408-3.015 <0.001 Primary suture closure 0.893 0.581-1.373 0.607 Duration of surgery 1.006 1.004-1.009 <0.001 Altemeier wound classification(15)
Clean 1.000 Clean contaminated 2.179 1.225-3.877 0.008 Contaminated 2.855 1.074-7.585 0.035 Dirty 6.346 1.442-27.938 0.015
Antibiotic treatment None 1.000 Prophylactic 1.251 0.865-1.808 0.234 Therapeutic 2.391 1.289-4.438 0.006
OR, odds ratio; AAA, aneurysm of the abdominal aorta; ASA, American Society of Anesthesiologists; EHS, European Hernia Society
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Precis
This registry-based cohort study of 2,191 patients identifies risk factors for postoperative
complications after incisional hernia surgery. After multivariate analysis, European Hernia
Society (EHS) width class was an independent risk factor for complication. The EHS
classification should be used in hernia publications and preoperative patient assessment.